Fruits, vegetables, and certain bottled waters are the most common sources of alkaline substances in everyday life. But “alkaline” means different things depending on context, so it helps to understand what you’re actually looking for: foods that produce an alkaline effect in your body, products with a high pH, or both.
How Alkalinity Actually Works
Anything with a pH above 7 is considered alkaline. Pure water sits at 7 (neutral), lemon juice lands around 2 to 2.6 (very acidic), and baking soda dissolved in water reaches about 8.3. Your blood stays in a tight alkaline range of 7.35 to 7.45 at all times, regulated by your lungs and kidneys. This means no food or drink meaningfully shifts your blood pH. What food can change is the pH of your urine, which is where the concept of “alkaline foods” comes from.
Researchers measure a food’s alkaline or acid effect on the body using something called the Potential Renal Acid Load, or PRAL score. A negative PRAL score means the food leaves an alkaline residue after digestion. A positive score means it leaves an acidic residue. This has little to do with whether the food itself tastes or tests as acidic. Lemons, for instance, are highly acidic in a glass but produce an alkaline effect once metabolized.
Foods With an Alkaline Effect
Fruits and vegetables are the two food groups with consistently negative (alkaline) PRAL scores. On average, fruits and fruit juices score about -3.1 per 100 grams, and vegetables score about -2.8. Some standouts go much further:
- Raisins: -21.0 per 100 grams, one of the most alkaline-forming foods measured
- Spinach: -14.0 per 100 grams
- Potatoes: -4.0 per 100 grams
- Apples: -2.2 per 100 grams
In general, leafy greens, root vegetables, bananas, citrus fruits, and dried fruits all fall on the alkaline side. The pattern is straightforward: the more fruits and vegetables you eat, the more alkaline your overall dietary load becomes. A diet heavy in these foods can shift average 24-hour urine pH from roughly 5.9 (mildly acidic) up to 6.6 or higher.
Foods That Are Acid-Forming
On the opposite end, hard cheeses top the charts. Parmesan scores 34.2 per 100 grams, and Gouda comes in at 18.6. Other acid-forming categories include grain products (bread at 7.0, pasta at 9.5), fish (7.9 on average), and meat. Chicken scores 8.7 and lean beef 7.8. Brown rice, perhaps surprisingly, scores 12.5. Fats and oils like butter and olive oil are essentially neutral at 0.
Milk is an interesting exception in the dairy group. While hard cheeses are among the most acid-forming foods, milk and noncheese dairy products actually score -2.8, placing them on the alkaline side.
Alkaline Water
Regular tap water typically has a neutral pH around 7. The EPA’s secondary standard for municipal drinking water is a pH range of 6.5 to 8.5. Commercial alkaline water brands push well above that range. Most bottled alkaline waters sit between pH 8 and 10, with brands like Essentia at 9.5 or higher, SmartWater Alkaline at 9+, and TEN Spring Water reaching a pH of 10. More moderately alkaline options include Flow at 8.1, Icelandic Glacial at 8.4, and Eternal at 8.2.
The higher pH in these products comes from added minerals or ionization processes. Whether that higher pH offers health benefits beyond basic hydration is a separate question, and the evidence for dramatic health effects is thin.
Household Products With Alkaline pH
Outside of food, many common household items are alkaline. Baking soda (pH around 8.3), most bar soaps (pH 9 to 10), household ammonia (pH around 11), bleach (pH around 12.5), and oven cleaners (pH 13 to 14) all sit on the alkaline end of the scale. Antacid tablets work precisely because they’re alkaline, neutralizing excess stomach acid on contact.
Do Alkaline Foods Improve Health?
The alkaline diet’s most popular claim is that eating alkaline-forming foods protects bones by reducing the acid your body needs to neutralize. The theory sounds logical, but the clinical evidence hasn’t kept up. The FDA reviewed the available human studies on alkaline compounds and osteoporosis risk and found that scientific conclusions could not be drawn from any of them. The studies had issues ranging from missing control groups to never measuring bone density after the intervention period.
That said, the foods that happen to be alkaline-forming, mainly fruits and vegetables, are well established as beneficial for dozens of other reasons: fiber, vitamins, minerals, and protective plant compounds. You don’t need to track PRAL scores to benefit from eating more spinach, potatoes, and fruit. The healthiest parts of an “alkaline diet” are healthy regardless of what they do to your urine pH.